1. Field of the Invention
The invention relates to a bush bearing, wherein the spring excursion of the elastomer bearing body is limited in the radial and/or axial direction by at least one limit stop. The invention also relates to a method for producing a correspondingly formed axial limit stop in a bush bearing.
2. Description of the Related Art
Elastomer rubber bearings, which are used in large numbers, in particular, in vehicle construction, for example for the wheel suspension, frequently have axial limit stops. The bearing body typically also has radial limit stops, if the elastomer bearing body includes cavities, such as pockets and the like, for achieving a predetermined radial characteristic. The limit stops limit the spring excursion of the elastomer bearing body under axial and/or radial loads. This prevents destruction of the bearing body by excess deformation or excess stress.
Bush bearings of this type include essentially a largely metallic inner part, and elastomer bearing body connected with the inner part by vulcanization, and an outer sleeve receiving both of the aforedescribed components, whereby the outer sleeve can also be connected with the bearing body by vulcanization. The bearing is typically installed at the desired installation site by pressing the outer sleeve of the bearing into a receiving lug.
Radial limit stops are produced, for example, by giving the inner part a particular shape or by applying a contour to the outer surface of the inner part. However, the manufacturing cost of a bush bearing increases significantly if the shape of the inner part deviates from a cylindrical shape or if the inner part has a variable outside diameter. It is also known to provide radial limit stops in bearings with cavities formed in the elastomer bearing body by inserting additional elements made of plastic or metal, whereby the elements are affixed in the cavities, for example with clips. However, these additional bearing components disadvantageously increase of the cost and complexity of assembly of bearings configured in this manner.
Axial limit stops for a bearing body can be formed in a number of ways. Frequently, an axial limit stop is implemented by forming on the end face of the outer sleeve a radially outwardly beaded flange. However, if an axial limit stop is formed by such flange on both sides, then the bearing can no longer be inserted into the intended receiving lug, because the outside diameter of the bearing is greater on both ends than in the remaining regions of the outer sleeve received by the receiving lug. In a conventional practical solution, this problem is avoided in bearings having an axial limit stop on both ends by forming the bearing in two sections split along the axial direction. Each of the two bearing sections is inserted in the bearing lug from a respective side and thereby connected with each other. However, implementing a bearing in two sections disadvantageously increases the costs. Installation of the bearing also becomes more complex which diminishes the productivity and increases cost.
DE 28 16 742 A1 describes a one-part bush bearing, whereby the aforedescribed problem is avoided by forming on one of the axial ends a radially outwardly oriented flange, while forming on the other axial end an inwardly oriented, so-called inside flange. Disadvantageously, however, the bearing reacts differently to positive axial and negative axial forces due to the different design of the two axial limit stops. In addition, the inwardly oriented surfaces of the inner flange restrict the geometric design and contour of the elastomer bearing body. Disadvantageously, this also limits of the calibration factor for adjusting the pretension in the elastomer bearing body. Moreover, the cardanic and torsion characteristic of the bearing cannot be influenced in the desired manner. Bearings designed in this manner therefore have typically a stiff cardanic and torsion characteristic, which increases the load of the bearing body under cardanic and torsion loads and reduces its service life. Pocket contours, which are frequently employed for adjusting the radial damping characteristic of the bearing, can frequently also not be designed to run continuous along the entire axial extent of the bearing. The asymmetric design of the axial bearing ends of the bearing may also cause the inner part to be inclined, which must be corrected by quenching and tempering, thus adding cost.